Batt



| H. MILLIGAN June 20, 1950 BATT Filed May 22, 1948 Inventor LOWELL H.MILL/GEN Patented June 20, 1950 BATT Lowell H. Milligan, Worcester,Mass, assignor to Norton Company, Worcester, Mass., a corporation ofMassachusetts Application May 22, 1948, Serial No. 28,690

The invention relates to batts for use in kilns, furnaces and the like.

One object of the invention is to provide a refractory batt capable ofwithstanding intense thermal shock. Another object of the invention isto provide a refractory batt capable of Withstanding irregular heatingor cooling of high differential, that-iswhere one part of the batt is ata different temperature from that of another part. Another object of theinvention is to provide a batt which is mechanically strong andresistant to heat shock and thermal differential. Another object of theinvention is to provide a batt of the character indicated of long life.Another object of theinvention is to provide a long-life batt oflargesize. Another'object is to provide a longlife batt for buildingstands of ware that are to bev heated and cooled from the directions ofthe edges of thebatts. Another object of the invention' is to providelong-life batts for use in a kiln provided with sources of heat aboveand/or below the batt; Another object of the invention is to provide around batt with one or more of the above characteristics. Other objectswill be in part obvious or in par pointedout hereinafter.- I w i Theinvention accordingl consists in the features of construction,combinations of elements and arrangements of parts all as will beillustratively described herein and the scope of the a plication of"which will be indicated in the following claims; -:';In theaccompanying drawings illustrating one of many possible embodiments ofthe mechanical features of this invention,

I Figurel is a plan view of the batt on a small scale,

Figure 2 is a fragmentary plan view of the batt on a larger scale,

Figure 3 is an elevation of the batt looking in the direction of thearrows v33 of Figure 2.

As conducive to a clearer understanding of the present invention, a battis a plate or other shape to hold ceramic or other ware during a heatingoperation. Thus, for example, green ceramic articles, such as unfiredmolded spark plugs, dishes or grinding wheels ar placed on batts whichare then put into or passed through a kiln, and the spark plugs,grinding wheels or dishes are fired,

that is to say, vitrified. The batt is therefore necessarily arefractory article.

Many ceramic manufacturers have estimated the cost of batts on the totalcost of their product and in practically all cases it has been foundthat the cost of batts is a large percentage of the cost 4 Claims. (01.-25153) of manufacturing the ceramic product which is sold. This is sobecause there is not merely a first cost of the batts but the cost ofcontinually replacing batts. A batt is cold when it is placed in a kilnbut becomes heated to the firing temperature or temperatures, usuallhigh, in the kiln, then it'is allowed to cool or may be rapidly cooledbyspecial means such as blowing air on it, and later on, after becomingcold, it is used again to support more green ware and is again heated,allowed to cool, and so on. Batts do not indefinitely survive thisalternate heating to high temperaturesand cooling even if thetemperature gradients are gentle; Eventually the batts break or crackand While a cracked batt may be used, it eventually becomes a brokenbatt and thereafter useful if at all only for smaller pieces of ware,and eventually, after further cracking or breaking, not at all. Theforegoing being true even when the slope of the temperature-time curveis very slightyit is all the more true and the percentage of the cost ofbatts to the total cost of manufacture of the product is much greaterwhen the slop of thetemperature-time curve is steep. Batts arecustomarily made of materials that are maturedto a strong condition attemperatures higher than those experienced by the batt in use. Thisgives aproduct having maximum stability in use against change indimensions, etc. It is advantageous to employ materials of as lowexpansivity' as feasible so as to reduce the amount of dimensionalchange and resulting stress as a function of temperature change. Battsand other kiln furniture hav long been made of refractory fire clays.These give products of satisfactory expansivity characteristics but ofrelatively low strength and low heat conductivity. Silicon carbide asthe main ingredient of batt mixtures gives improved products because inaddition to'lowexpansivity they'have high strength andhigh heatconductivity. Likewise, batts composed of mullite which mullite may havebeen essentially originally of the electric furnace fused variety, ormay have been developed by the maturing operation to which the batt wassubjected in manufacture, hav advantages over fire clay batts.Furthermore; refractory'batts for very high temperature use "m-ay now bemade as sintered or recrystallized products, often substantiallybondless, many of which may be classed as pure oxide refractories. Thisinvention, although described particularly for silicon carbide products,is also advantageous when embodied in batts composed of other refractorymaterials.

As an example of a bonded silicon carbide composition for battsaccording to the present invention, I may make a mixture according tothe following formula:

The silicon carbide is the ordinary black-grade and is put into a mixingmachine of conventional type and the dextrine is added. After mixingfora minute or two the water is added and mixing is continued for-aminuteortwdmore; Then: the balliclay: and rye-.fiour are screenedintothemix together: and the; mixing is; continued 1' for five minutesmore.This-:pr.ocedure. producesaxdamp granular mixture that is suitable fortamping or pressing.

Figures 1. 2iand3'show. anzrexample of: a batt according: to this:invention; This is round and flat, thatis to' say it'xisza circular.disc-and may or may not have a central hole it. Preferably it has anessentially flat side Hand anessentiallyfiat sidel'z bound byacylindrica'l edge: l3.- Although theside ll isshownzas thetop sideandtherside l 2 as the bottom side, the batt is reversible in the examplegiven,

The batt has apluralitynof?indentations arranged in clusters l5, eachcluster'of indentations being elongated and 'extending-in-radiaidirections from the periphery or, edge :l-Sltowardfthe: center of thebatt but preferably stoppingishortt thereof and. each indentationextendingzfrom asurface H or I2, therebeing-preferably:ineachucluster atleast oneindentationfrom each surface. This construction is:accordion-like with the indentations running radially so that;differences. Ofx expansicn-betweenconcentric circlesof tthetbatt areaccommodated-and will nottcrack the..batt;.

The invention can havema'ny practical embodiments but forillustration:there'is herein disclosed the best embodimentnow: lmowntor me which issimple, well balanced, and easy to: manufacture. Thus, and referring nowespecially to Figure 3, each cluster!Ecomprisesthreeradially extendingtapered bores l6, l1 and IBceXtending fromthe periphery orredge 13 abouthalf way. to the center ofthe batt, the;bores:: lS-and [8 beingconnected by straight slots: l9: and with: the surface I2 andthe bore I!being: connected. by a straight: slot 2|: with the surface: H. As-illustrated, thebores; i 6, 1 land; I 8; are. all of the-same dimensions"and. likewise the: slots l9; 20 and 21 are'of' the same dimensions;-:,This-radialiboring and. slotting off thev batti leaves: connecting wallportions. 22; and 23 asiwell as; connecting wall portions-24, 25;and26;which, being-thinner than the: total thickness of theabatt can flexsomewhat more-than a solidbattcould flex without breakage and;furthermore if, each one; of; the portions: 2.3 to- 25 flexes: a littlebit, the total deformation without breakage can be much greater thancould the total deformation in the case of a solid batt.

In a circular batt the greatest strains and stresses are likely to beset up near the periphery. Furthermore, such strains and stresses areexerted along concentric circles. By the construction describedthesestrains and stresses are adequately absorbedup to extremeconditions of differential heating or thermal shock.

It will thus be seen that there has been provided by this invention abatt in which the various objects hereinabove set forth together withmany thoroughly practical advantages are successfully achieved. As manypossible embodiments may bepmad-e, ofthe above invention and as manychanges might be made in the embodiments above. set forth, it is to beunderstood that all matter hereinbefore set forth or shown in theaccompanying drawings is to be interpreted as illustrative and not in alimiting sense.

I claim:

1. A batt for kilns, furnaces andthe like genorally inthe form of a"circular disc; having a plurality of clusters of indentations eachcluster being elongated and extend'ingin radial directions from theperiphery'towardsthe center oftheibatt and each cluster comprising'boresconnected by straight slots with a: surface ofthe batt the slots beingtapered inwardly towards. the center of the batt;

2; A batt for kilns, furnaces'and thelike generally in the form of acircular" disc; having a plurality of clusters ofindentations'eachcluster being elongated and extendin in radialdirections from the periphery towards the-center ofthe batt and eachcluster comprisingbores connected by straight slots with a surface ofthe batt the slots being tapered inwardly towards the center of the battand each cluster' having at least one slot'extending from eachsurfaceofthebatt.

3. A batt for kilns, furnaces and: the likegenerally in the form of acircular disc, having aplu ralityo-f clusters of indentations eachcluster-being elongated and extending in-radial' directions fromtheperiphery towards the center of the batt, there being an indentation ineachsideof-the batt in each cluster, each indentationextendlng from-asurface of-the batt at least halfway to the other surface of the baitalong the major portionof its length but the indentations anotextendingclearthrough' the batt along any considerable radial distance, and therebeing between the indentations wall portions of the batt whichare'thinner than'the total thickness of the bait;

4. A batt according to claim3' in which-the indentations are taperedinwardly towards the center of the batt.

LOWELL H. MLHGAN;

REFERENCES CITED The following references are of record in th file ofthis patent:

UNITED STATES PATENTS lf urrlbe Name- Date 1,215,067 Simonds Feb. 6;191'? 1,485,110 Beth Feb. '26; 1924 1,393,123 Beth Jan; 8, 1938

